This invention generally relates to a fusing apparatus and, more particularly, to a machine for fusing the armature wires of an electric motor to a tang or slot of a commutator bar and for fusing wires to stator hooks.
Although fusing machines are widely known, more precise, efficient and economical machines are greatly needed. Existing methods for the mechanical manipulation and control of a fusing electrode as related to both armature tang fusing and stator terminal fusing include pneumatically driven slides as well as ball screw driven slides controlled by a servo motor. Pneumatics have proven to be functional but include inherent deficiencies. They are not easily adjusted for fine tuning of the fusing forces. A pressure regulator may be adjusted, which will increase or decrease the fusing force, but does not give the user an actual reading of the forces since the driving cylinder output force is not directly obtainable from the regulator gauge. Alternatively, the tension on a spring results in a non-precision change in the fusing forces.
The use of servo motors to regulate the fusing forces as shown in U.S. Pat. No. 5,063,279 to Axis USA, Inc. has also proven to be inefficient. Servo motors are excellent devices for fast, accurate positioning but they are not designed to be torque limiters. Even with external force feedback gauges it is very difficult, if not impossible, to design a control system fast enough to react to a rapidly changing force curve relating the position of a ball screw driven by a servo motor to a known, constant fusing force. Another limiting factor with a servo motor is cost. Servo systems are both expensive and costly to maintain in severe applications.
One difficulty in regulating the fusing operation is in detecting that the electrode has contacted the tang. It has been proposed to use a load cell for this purpose but the force of the tang against the electrode is so small compared to the weight of the fusing head that it is very difficult to sense tang contact with a load cell. Therefore, a need exists for an improved fusing apparatus that eliminates the problems associated with previous fusing machines, produces uniform connections, and provides for an easy, quick-change of the electrode.